Torque applied to a 8-32 SCHS

[cobb]

Can anyone tell me how much torque can be applied to a 8-32 Stainless steel Socket cap head bolt that is 3-1/2" long ?

Thanks
Cobb

Scott Cobb
CSM Manufacturing, Inc
csm-mfg.com

 

[CoryPad]

Does the joint have a preload requirement? What is the screw material yield strength? Any screw coating/lubricant? What are the materials for the clamped parts and the mating nut? What is the hole size and screw head size? If the joint is not critical (based on your minimal information, I assume this to be correct), how about snug plus 90-120 degrees rotation?

 

[fastech]

Hello Cobb;
Once again Corypad is right. If we can make some assumptions that the stainless you are using is ASTM F593 speced, and you use 75% of the yield for this product, and assuming that the 'sandwich' you are working is a 'fairly' stiff joint not in excess of 1.25"; and that there is no coating on the screw other than the normal passivation for stainless, then that makes the coefieient of friction for the joint roughly 0.275; the applied torque then comes out to be 28.4 Lbf-in.

At 95% of yield that torque figure becomes roughly 36.0 Lbf-in. This level of use is not recommended. I like to stay in the 65% - 75% range.

By the way, the 65% level is roughly 24.6 Lbf-in.

I am using BoltSciences TORKSense software to determine these numbers.
Be sure to follow up with verification testing.


fastech

Bill P.
CSFT, Inc.

 

[cobb]

Thanks for the info.

Scott Cobb
CSM Manufacturing, Inc
csm-mfg.com